Method of manufacturing quartz crystal resonator and quartz crystal resonator unit

ABSTRACT

A method of forming a quartz crystal resonator is provided with the resonator including a body portion with first and second main surfaces facing each other and, in plan view having a pair of long sides extending in a first direction and a pair of short sides extending in a second intersecting direction. Moreover, first and second excitation electrodes are formed on the respective main surfaces; a frame surrounds the body portion at both ends and is separated from the both ends; and first and second coupling portions extend from the short sides and with widths of the short sides. At least one of the first and second coupling portions is formed with a thickness in a third direction is smaller than a thickness in the third direction of a region of the body portion where the first excitation electrode and the second excitation electrode face each other.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation U.S. patent application Ser.No. 16/576,909, filed Sep. 20, 2019, which is a continuation ofPCT/JP2018/018672 filed May 15, 2018, which claims priority to JapanesePatent Application No. 2017-096648, filed May 15, 2017, the entirecontents of each of which are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a quartz crystal resonator and a quartzcrystal resonator unit in each of which a quartz crystal blank and aquartz crystal frame body surrounding the quartz crystal blank arecoupled to each other by quartz crystal coupling members, and to methodsof manufacturing the quartz crystal resonator and the quartz crystalresonator unit.

BACKGROUND

In general, piezoelectric devices having a structure in which apiezoelectric chip is interposed between a lid and a base are widelyused as piezoelectric devices used in an oscillation device, a band passfilter, and the like. For example, Patent Document 1 (identified below)describes a specific example of such a piezoelectric chip in which avibration portion and a frame surrounding the vibration portion arecoupled to each other by one coupling portion and with a through portionthat is formed between the frame portion and a periphery of thevibration portion excluding the coupling portion. For example, theentirety of the piezoelectric chip is made by wet etching an AT-cutquartz crystal plate.

Patent Document 1: Japanese Unexamined Patent Application PublicationNo. 2016-201624.

Because a quartz crystal has an anisotropic crystal structure, thedissolution rate of wet etching differs in accordance with crystalorientation. Accordingly, when a quartz crystal substrate is wet etched,for example, in a step of forming a through portion, dissolution doesnot proceed in the normal line direction of a main surface of the quartzcrystal substrate but proceeds with an inclination. Thus, in order toform a through portion along substantially the entire periphery of thevibration portion as described in Patent Document 1, depending oncrystal orientation, it is necessary to provide a comparatively largedistance between the vibration portion and the frame. That is, if thesize of the piezoelectric chip is reduced in the conventional structure,the area of the vibration portion decreases and vibrationcharacteristics may deteriorate. On the other hand, if providing anappropriate area to the vibration portion is prioritized, a problemarises in that the outer size of the piezoelectric chip increases.

SUMMARY OF THE INVENTION

Accordingly, the present invention has been made in such circumstances,and an object thereof is to provide a quartz crystal resonator and aquartz crystal resonator unit each of which can be reduced in size whilesuppressing deterioration of vibration characteristics. Moreover,methods are provided for manufacturing the quartz crystal resonator andthe quartz crystal resonator unit.

According to an exemplary aspect of the present invention, a quartzcrystal resonator is provided that includes a body portion that has afirst main surface and a second main surface facing each other and thathas, in plan view as seen from the first main surface side or the secondmain surface side, a pair of long sides that extend in a first directionand a pair of short sides that extend in a second direction thatintersects the first direction. Moreover, a first excitation electrodeis provided that is disposed on the first main surface; a secondexcitation electrode is provided that is disposed on the second mainsurface so as to face the first excitation electrode; a frame surroundsthe body portion and is disposed, at both end portions of the bodyportion in the second direction, separated from the both end portions; afirst coupling portion extends from one of the pair of short sides ofthe body portion in the first direction with a width of the short sideand that couples the body portion and the frame to each other; and asecond coupling portion extends from the other of the pair of shortsides of the body portion in the first direction with a width of theshort side and that couples the body portion and the frame to eachother. In the exemplary aspect, the body portion, the frame, the firstcoupling portion, and the second coupling portion are each made of aquartz crystal. In addition, at least one of the first coupling portionand the second coupling portion has a portion whose thickness in a thirddirection is smaller than a thickness in the third direction of a regionof the body portion where the first excitation electrode and the secondexcitation electrode face each other, with the third direction being adirection that intersects the first direction and the second direction.

A quartz crystal resonator according to another exemplary aspect of thepresent invention includes a body portion that has first and second mainsurfaces facing each other and that has, in plan view as seen from thefirst main surface side or the second main surface side, a pair of longsides that extend in a first direction and a pair of short sides thatextend in a second direction that intersects the first direction.Moreover, the resonator includes a first excitation electrode that isdisposed on the first main surface; a second excitation electrode thatis disposed on the second main surface so as to face the firstexcitation electrode; a frame portion that has an inner side surfacethat is located so as to surround the body portion and an upper surfaceand a lower surface that are respectively located on an upper side and alower side in a third direction that intersects the first direction andthe second direction; a first coupling portion that extends in the firstdirection so as to couple one of the pair of short sides of the bodyportion to the inner side surface of the frame portion with a width ofthe short side and that has an upper surface and a lower surface thatare respectively located on an upper side and a lower side in the thirddirection; and a second coupling portion that extends in the firstdirection so as to couple the other of the pair of short sides of thebody portion to the inner side surface of the frame portion with a widthof the short side and that has an upper surface and a lower surface thatare respectively located on an upper side and a lower side in the thirddirection. Between both ends of the body portion in the second directionand the frame portion, a first through portion and a second throughportion are formed so as to each extend over a length of the bodyportion, the first coupling portion, and the second coupling portion inthe first direction. The first main surface and the second main surfaceare located between the upper surface and the lower surface of the frameportion in the third direction. The upper surface and the lower surfaceof the first coupling portion each have an inclined portion that isinclined upward in the third direction from the body portion toward theframe portion. Moreover, the upper surface and the lower surface of thesecond coupling portion each have an inclined portion that is inclineddownward in the third direction from the body portion toward the frameportion.

In another exemplary aspect, a method of manufacturing a quartz crystalresonator is provided that includes (a) preparing a first substrate thatis made of a quartz crystal that is AT-cut in such a way that, when anX-axis, a Y-axis, and a Z-axis are crystal axes of the quartz crystaland a Y′-axis and a Z′-axis are respectively axes that are obtained byrotating the Y-axis and the Z-axis around the X-axis by a predeterminedangle in a direction from the Y-axis toward the Z-axis, surfaces of thequartz crystal that are defined by the X-axis and the Z′-axis are mainsurfaces. Moreover, the method includes (b) forming, by wet etching thefirst substrate, a body portion that has a first main surface and asecond main surface facing each other and that has, in plan view as seenfrom the first main surface side or the second main surface side, a pairof long sides that extend in the Z′-axis direction and a pair of shortsides that extend in the X-axis direction, a frame portion thatsurrounds the body portion, and a first coupling portion and a secondcoupling portion that couple the body portion and the frame portion toeach other at both end portions of the body portion in the Z′-axisdirection. The method further includes (c) forming a first excitationelectrode on the first main surface and forming a second excitationelectrode that faces the first excitation electrode on the second mainsurface. In the exemplary aspect, the step (b) includes separating bothend portions of the body portion in the X-axis direction from the frameportion, extending the first coupling portion in the Z′-axis directionfrom one of the pair of short sides of the body portion with a width ofthe short side to reach the frame portion, extending the second couplingportion in the Z′-axis direction from the other of the pair of shortsides of the body portion with a width of the short side to reach theframe portion, and making a thickness in the Y′-axis direction of atleast a portion of at least one of the first coupling portion and thesecond coupling portion smaller than a thickness in the Y′-axisdirection of a region of the body portion where the first excitationelectrode and the second excitation electrode face each other.

In another exemplary aspect, a method of manufacturing a quartz crystalresonator is provided that includes (a) preparing a first substrate thatis made of a quartz crystal that is AT-cut in such a way that, when anX-axis, a Y-axis, and a Z-axis are crystal axes of the quartz crystaland a Y′-axis and a Z′-axis are respectively axes that are obtained byrotating the Y-axis and the Z-axis around the X-axis by a predeterminedangle in a direction from the Y-axis toward the Z-axis, surfaces of thequartz crystal that are defined by the X-axis and the Z′-axis are mainsurfaces. Moreover, the method includes (b) forming, by wet etching thefirst substrate, a body portion that has a first main surface and asecond main surface facing each other and that has, in plan view as seenfrom the first main surface side or the second main surface side, a pairof long sides that extend in the Z′-axis direction and a pair of shortsides that extend in the X-axis direction, a frame portion that has aninner side surface that is located so as to surround the body portionand an upper surface and a lower surface that are respectively locatedon an upper side and a lower side in the Y′-axis direction, a firstcoupling portion that extends in the Z′-axis direction so as to coupleone of the pair of short sides of the body portion and the inner sidesurface of the frame portion to each other with a width of the shortside and that has an upper surface and a lower surface that arerespectively located on an upper side and a lower side in the Y′-axisdirection, a second coupling portion that extends in the Z′-axisdirection so as to couple the other of the pair of short sides of thebody portion and the inner side surface of the frame portion to eachother with a width of the short side and that has an upper surface and alower surface that are respectively located on an upper side and a lowerside in the Y′-axis direction, and a first through portion and a secondthrough portion between both end portions of the body portion in theX-axis direction and the frame portion, the first and second throughportions each extending over a length of the body portion, the firstcoupling portion, and the second coupling portion in the Z′ axisdirection. The method further includes (c) forming a first excitationelectrode on the first main surface and forming a second excitationelectrode that faces the first excitation electrode on the second mainsurface. According to the exemplary aspect, in step (b), the first mainsurface and the second main surface are located between the uppersurface and the lower surface of the frame portion in the Y′-axisdirection, an inclined portion is formed in each of the upper surfaceand the lower surface of the first coupling portion, the inclinedportion being inclined upward in the Y′-axis direction from the bodyportion toward the frame portion, and an inclined portion is formed ineach of the upper surface and the lower surface of the second couplingportion, the inclined portion being inclined downward in the Y′-axisdirection from the body portion toward the frame portion.

According to the exemplary aspects of the present invention, a quartzcrystal resonator and a quartz crystal resonator unit are provided thatcan have a reduced size while suppressing deterioration of vibrationcharacteristics. Moreover, methods of manufacturing the quartz crystalresonator and the quartz crystal resonator unit are also provided.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an exploded perspective view of a quartz crystal resonatorunit 1 according to a first exemplary embodiment of the presentinvention.

FIG. 2 is a plan view of a quartz crystal blank 110 according to thefirst exemplary embodiment of the present invention as seen from a mainsurface 112 side.

FIG. 3 is a plan view of the quartz crystal blank 110 according to afirst exemplary embodiment of the present invention as seen from a mainsurface 114 side.

FIG. 4 is a sectional view taken along line IV-IV in FIG. 1.

FIG. 5 is a perspective view of the quartz crystal resonator unit 1according to the first exemplary embodiment of the present invention.

FIG. 6 is a flowchart illustrating a method of manufacturing the quartzcrystal resonator unit 1 according to the first exemplary embodiment ofthe present invention.

FIG. 7 is a sectional view illustrating how dissolution occurs when aportion between a quartz crystal blank and a frame body is etched.

FIG. 8 is a sectional view of a quartz crystal resonator 500 accordingto a second exemplary embodiment of the present invention in which,specifically, an extension electrode is different in a sectional viewsimilar to FIG. 4.

FIG. 9 is a sectional view of a quartz crystal resonator 600 accordingto a third exemplary embodiment of the present invention in which,specifically, a quartz crystal blank is different in a sectional viewsimilar to FIG. 4.

DETAILED DESCRIPTION OF EMBODIMENTS

Hereinafter, exemplary embodiments of the present invention will bedescribed. In the following descriptions related to the drawings, thesame or similar elements are denoted by the same or similar numerals. Itshould be appreciated that the drawings are exemplary, the dimensionsand the shapes of elements are schematic, and the technical scope of thepresent invention is not limited to the embodiments.

Referring to FIGS. 1 to 5, a quartz crystal resonator unit according toa first exemplary embodiment of the present invention will be described.FIG. 1 is an exploded perspective view of a quartz crystal resonatorunit 1 according to the first embodiment. FIG. 2 is a plan view of aquartz crystal blank 110 according to the first embodiment as seen froma main surface 112 side. FIG. 3 is a plan view of the quartz crystalblank 110 according to a first embodiment as seen from a main surface114 side. FIG. 4 is a sectional view taken along line IV-IV in FIG. 1.FIG. 5 is a perspective view of the quartz crystal resonator unit 1according to the first embodiment.

As illustrated in FIG. 1, the quartz crystal resonator unit 1 accordingto the present embodiment includes a quartz crystal resonator 100, a lidmember 200 (also referred to as a “lid”), and a base member 300 (alsoreferred to as a “base”). It is noted that with referent to FIG. 1,outer electrodes described below are omitted.

According to the exemplary aspect, the quartz crystal resonator 100, thelid member 200, and the base member 300 are each made from an AT-cutquartz crystal substrate. The AT-cut quartz crystal substrate is cut outso that, when an X-axis, a Y-axis, and a Z-axis are the crystal axes ofa quartz crystal and a Y′-axis and a Z′-axis are respectively axes thatare obtained by rotating the Y-axis and the Z-axis around the X-axis by35 degrees 15 minutes±1 minute 30 seconds in a direction from the Y-axistoward the Z-axis, the quartz crystal substrate has main surfaces thatare parallel to a surface defined by the X-axis and the Z′-axis. TheX-axis, the Z′-axis, and the Y′-axis intersect each other, and accordingto the present embodiment, perpendicularly intersect each other. In thepresent embodiment, a quartz crystal substrate that is AT-cut from asynthetic quartz crystal is used in the quartz crystal resonator. Aquartz crystal resonator using an AT-cut quartz crystal substrate isgenerally used with a thickness shear vibration mode as a mainvibration. Hereinafter, elements of the quartz crystal resonator unitwill be described with reference to the axial direction of the AT-cutquartz crystal.

The quartz crystal resonator 100 includes the quartz crystal blank 110,a frame body 120 (also referred to as a “frame”) that surrounds theouter periphery of the quartz crystal blank 110, and coupling members111 a and 111 b that couple the quartz crystal blank 110 to the framebody 120. The quartz crystal blank 110, the frame body 120, and thecoupling members 111 a and 111 b are each made from an AT-cut quartzcrystal substrate. Hereinafter, referring to FIGS. 2 to 4, elements ofthe quartz crystal resonator 100 will be described in detail.

The quartz crystal blank 110 is a body portion of the quartz crystalresonator 100 and has a flat plate-like shape having two main surfacesfacing each other. To be specific, the quartz crystal blank 110 has themain surface 112 (i.e., a first main surface) on the positive Y′-axisside and the main surface 114 (i.e., a second main surface) on thenegative Y′-axis side. As described below, the quartz crystal blank 110and the coupling members 111 a and 111 b are continuously formed.However, in the present embodiment, for convenience of description, mainsurfaces of a region corresponding to the quartz crystal blank 110, thatis, a region of the quartz crystal resonator 100 excluding the couplingmembers 111 a and 111 b and the frame body 120 will be referred to asthe main surfaces 112 and 114. As described above, the quartz crystalblank 110 and the coupling members 111 a and 111 b may be continuouslyformed without being distinguished from each other.

In plan view as seen from the main surface 112 side and in plan view asseen from the main surface 114 side, the quartz crystal blank 110 has apair of long sides (long sides of the main surfaces 112 and 114) thatare parallel to the Z′-axis (e.g., a first direction) and a pair ofshort sides (short sides of the main surfaces 112 and 114) that areparallel to the X-axis (e.g., a second direction). Moreover, the quartzcrystal blank 110 has a thickness in a direction parallel to the Y′-axis(e.g., a third direction) (hereinafter, the thickness in the directionparallel to the Y′-axis will be simply referred to as the “thickness”).In the exemplary embodiments herein, the long sides, the short sides,and sides in the thickness direction of the quartz crystal blank 110 areparallel to the corresponding axes. However, the present invention isnot limited to this. As long as the sides of the quartz crystal blank110 extend along the axes, the sides need not be strictly parallel tothe axes. The same applies to a quartz crystal blank 610 describedbelow. The quartz crystal blank 110 is separated from the frame body120, and the quartz crystal blank 110 and the frame body 120 are coupledto each other by the two coupling members 111 a and 111 b. Moreover, thequartz crystal blank 110 is configured to vibrate at a predeterminedfrequency.

The frame body 120 is a frame portion of the quartz crystal resonator100. In plan view as seen from the main surface 112 side of the quartzcrystal blank 110 or in plan view as seen from the main surface 114side, the frame body 120 surrounds the outer periphery of the quartzcrystal blank 110 in the Z′X-plane. To be specific, at both end portions(also referred to as “ends”) of the quartz crystal blank 110 in theZ′-axis direction, the frame body 120 is coupled to the quartz crystalblank 110 by the coupling members 111 a and 111 b; and, at both endportions of the quartz crystal blank 110 in the X-axis direction, theframe body 120 is separated from the both end portions withpredetermined clearances. That is, as illustrated in FIGS. 2 and 3, athrough portion 113 a (i.e., a first through portion) and a throughportion 113 b (i.e., a second through portion) are interposed betweenboth end portions of the quartz crystal blank 110 in the X-axisdirection and the frame body 120. The through portions 113 a and 113 beach extend over a length that is the sum of the lengths of the quartzcrystal blank 110 and the coupling members 111 a and 111 b in theZ′-axis direction. The frame body 120 has an upper surface 122 on themain surface 112 side of the quartz crystal blank 110, a lower surface124 on the main surface 114 side of the quartz crystal blank 110, aninner side surface facing the quartz crystal blank 110, and an outerside surface on the outside. The frame body 120 is a frame portion thatis joined to the lid member 200 and the base member 300 described below.The thickness of the frame body 120 is larger than the thickness of thequartz crystal blank 110, and a space in which the quartz crystal blank110 can vibrate is formed when the lid member 200 and the base member300 are joined to the quartz crystal resonator 100. In other words, themain surface 112 and the main surface 114 of the quartz crystal blank110 are located between the upper surface 122 and the lower surface 124of the frame body 120 in the Y′-axis direction.

The coupling member 111 a (i.e., a first coupling portion) and thecoupling member 111 b (i.e., a second coupling) are coupling portionsthat couple the quartz crystal blank 110 and the frame body 120 to eachother and are disposed at both ends of the quartz crystal blank 110 inthe Z′-axis direction. The coupling member 111 a extends in the positiveZ′-axis direction (e.g., a first direction) from one of the pair ofshort sides of the quartz crystal blank 110 on the positive Z′-axis side(one end side) while keeping the length of the short side in the X-axisdirection (hereinafter, referred to as the “width”) and couples thequartz crystal blank 110 and the frame body 120 to each other. Thecoupling member 111 b extends in the negative Z′-axis direction (e.g.,the first direction) from the other of the pair of short sides of thequartz crystal blank 110 on the negative Z′-axis side (the other endside) while keeping the width of the short side and couples the quartzcrystal blank 110 and the frame body 120 to each other. That is, thequartz crystal blank 110 and the coupling members 111 a and 111 b arecontinuously disposed in such a way that both side surfaces of thequartz crystal blank 110, which are located at both end portions in theX-axis direction and which extend in the Z′-axis direction, and bothside surfaces of the coupling member 111 a and the coupling member 111b, which are located at both end portions in the X-axis direction andwhich extend in the Z′-axis direction, have common surfaces thatcontinuously extend in the Z′-axis direction. Thus, the lengths of thecoupling members 111 a and 111 b in the X-axis direction are, forexample, substantially the same as the lengths of the short sides of thequartz crystal blank 110. Before describing the details of the shapes ofthe coupling members 111 a and 111 b, electrodes formed in the quartzcrystal resonator 100 will be described.

As illustrated in FIGS. 2 and 3, an excitation electrode 130 (referredto as a first excitation electrode) is formed on the main surface 112 ofthe quartz crystal blank 110, and an excitation electrode 140 (referredto as a second excitation electrode) is formed on the main surface 114.The excitation electrode 130 and the excitation electrode 140 face eachother with the quartz crystal blank 110 therebetween and substantiallyoverlap each other (in the thickness direction) with the quartz crystalblank 110 therebetween.

An extension electrode 132 (referred to as a first extension electrode),which is electrically connected the excitation electrode 130, is formedon the upper surface 122 of the frame body 120. An extension electrode142 (referred to as a second extension electrode), which is electricallyconnected the excitation electrode 140, is formed on the lower surface124 of the frame body 120. As illustrated in FIG. 2, the extensionelectrode 132 extends from the excitation electrode 130 via the couplingmember 111 a to the upper surface 122 of the frame body 120 and extendsto reach an outer side surface on the positive Z′-axis side. Asillustrated in FIG. 3, the extension electrode 142 extends from theexcitation electrode 140 via the coupling member 111 b to the lowersurface 124 of the frame body 120 and extends to reach an outer sidesurface on the negative Z′-axis side. Thus, on both end surfaces of thequartz crystal resonator 100 in the Z′-axis direction, it is possible toform outer electrodes that are electrically connected to a correspondingone of the excitation electrodes 130 and 140 via the extensionelectrodes 132 and 142. The directions in which the extension electrodes132 and 142 extend are not limited to both end portions in the Z′-axisdirection. For example, the directions in which the extension electrodes132 and 142 extend may be both end portions in the X-axis direction. Inaccordance with positions where outer electrodes are to be formed, thedirections in which the extension electrodes 132 and 142 extend may bechanged as appropriate.

In the present embodiment, the extension electrode 132 extends along theentire periphery of the upper surface 122 of the frame body 120 asillustrated in FIG. 2, and the extension electrode 142 extends along theentire periphery of the lower surface 124 of the frame body 120 asillustrated in FIG. 3. Moreover, in plan view as seen from the positiveY′-axis direction, the extension electrodes 132 and 142 are disposed insuch a way that at least parts thereof do not overlap each other in thethickness direction. To be specific, in the example illustrated in FIGS.2 and 3, excluding a region on the positive Z′-axis side, the extensionelectrode 132 is disposed near the inner periphery of the frame body120, and the extension electrode 142 is disposed near the outerperiphery of the frame body 120. Thus, the distance between theextension electrode 132 and the extension electrode 142 via the framebody 120 is long, and parasitic capacity that may be generated betweenthe extension electrodes is reduced. Accordingly, the effect of noisefrom one of the extension electrodes on the other extension electrode isreduced.

Because the extension electrodes 132 and 142 extend to end surfaces ofthe quartz crystal resonator 100 as described above, it is possible toelectrically connect the excitation electrodes 130 and 140 to theoutside of the quartz crystal resonator unit 1 via the end surfaces ofthe quartz crystal resonator 100.

Next, referring to FIG. 4, the shapes of the coupling members 111 a and111 b will be described in detail. As illustrated in FIG. 4, thecoupling members 111 a and 111 b respectively have portions whosethicknesses Ha and Hb in the Y′-axis direction are smaller than thethickness Hc of a region of the quartz crystal blank 110 where theexcitation electrode 130 and the excitation electrode 140 face eachother.

More particularly, the coupling member 111 a has an upper surface 116 aon the main surface 112 side of the quartz crystal blank 110(hereinafter, the positive Y′-axis side (one side) may be referred to asthe “upward direction”) and a lower surface 118 a on the main surface114 side of the quartz crystal blank 110 (hereinafter, the negativeY′-axis side (the other side) may be referred to as the “downwarddirection”). The upper surface 116 a of the coupling member 111 a has aninclined portion that is inclined in the upward direction with respectto the main surface 112 from the quartz crystal blank 110 toward theframe body 120. The lower surface 118 a of the coupling member 111 a hasan inclined portion that is inclined in the upward direction withrespect to the main surface 114 from the quartz crystal blank 110 towardthe frame body 120. Because the lower surface 118 a is inclined in theupward direction (positive Y′-axis direction) in this way, a portion ofthe coupling member 111 a whose thickness Ha is smaller than thethickness Hc of the quartz crystal blank 110 is formed.

As further shown, the coupling member 111 b has an upper surface 116 bin the upward direction and a lower surface 118 b in the downwarddirection. The upper surface 116 b of the coupling member 111 b has aninclined portion that is inclined in the downward direction with respectto the main surface 112 from the quartz crystal blank 110 toward theframe body 120. The lower surface 118 b of the coupling member 111 b hasan inclined portion that is inclined in the downward direction withrespect to the main surface 114 from the quartz crystal blank 110 towardthe frame body 120. Because the upper surface 116 b is inclined in thedownward direction (i.e., the negative Y′-axis direction) in this way, aportion of the coupling member 111 b whose thickness Hb is smaller thanthe thickness Hc of the quartz crystal blank 110 is formed.

To be more specific, the upper surface 116 a of the coupling member 111a has a shape such that, from the main surface 112 of the quartz crystalblank 110 to the upper surface 122 of the frame body 120, an inclinedportion 116 ax, which is connected to the main surface 112 and has arecessed shape that opens in the upward direction, connects the mainsurface 112 and the upper surface 122 of the frame body 120 to eachother. The lower surface 118 a of the coupling member 111 a has a shapesuch that, from the main surface 114 of the quartz crystal blank 110 tothe inner side surface of the frame body 120, an inclined portion 118ax, which has a recessed shape that opens in the downward direction, anda flat surface portion 118 ay, which has a planar shape parallel to themain surface 114 of the quartz crystal blank 110, connect the mainsurface 114 and the inner side surface of the frame body 120 to eachother. The upper surface 116 b of the coupling member 111 b has a shapesuch that, from the main surface 112 of the quartz crystal blank 110 tothe inner side surface of the frame body 120, an inclined portion 116bx, which has a recessed shape that opens in the upward direction, and aflat surface portion 116 by, which has a planar shape parallel to themain surface 112 of the quartz crystal blank 110, connect the mainsurface 112 and the inner side surface of the frame body 120 to eachother. The lower surface 118 b of the coupling member 111 b has a shapesuch that, from the main surface 114 of the quartz crystal blank 110 tothe lower surface 124 of the frame body 120, an inclined portion 118 bx,which is connected to the main surface 114 and has a recessed shape thatis open in the downward direction, connects the main surface 114 and thelower surface 124 of the frame body 120 to each other. In other words,the inclined portion 116 ax and the inclined portion 116 bx each have acurved shape that is recessed downward, and the inclined portion 118 axand the inclined portion 118 bx each have a curved shape that isrecessed upward. Thus, the coupling members 111 a and 111 b each have ashape such that, from the inside toward the outside of the quartzcrystal resonator 100, the thickness thereof monotonously decreases andthen monotonously increases. The upper surface 116 a of the couplingmember 111 a and the upper surface 122 of the frame body 120 may beconnected to each other in such a way that the boundary therebetween isshaped like a curved surface. Such a boundary shape also applies to theboundary between the lower surface 118 a of the coupling member 111 aand the main surface 114 of the quartz crystal blank 110, the boundarybetween the upper surface 116 b of the coupling member 111 b and themain surface 112 of the quartz crystal blank 110, and the boundarybetween the lower surface 118 b of the coupling member 111 b and thelower surface 124 of the frame body 120. It is noted the that exemplaryembodiment can be modified in which any or all of the upper surfaces 116a and 116 b and the lower surfaces 118 a and 118 b are flat surfaces ora modification in which these surfaces are a combination flat surfacesand cured surfaces according to variations of the exemplary embodiment.

In the example illustrated in FIG. 4, the quartz crystal blank 110, thecoupling members 111 a and 111 b, and the frame body 120 each have ashape that is point-symmetric about the center of the quartz crystalblank 110 (not shown) in the Y′Z′-plane. That is, the upper surface 116a and the lower surface 118 b have the same shape, and the lower surface118 a and the upper surface 116 b have the same shape.

With the structure described above, the thicknesses of the quartzcrystal blank 110 and the coupling members 111 a and 111 b and thethicknesses of the coupling members 111 a and 111 b and the frame body120 differ from each other at the boundaries therebetween. Thus, whilethe quartz crystal blank 110 is supported by the frame body 120 via thecoupling members 111 a and 111 b, leakage of vibration of the quartzcrystal blank 110 to the frame body 120 via the coupling members 111 aand 111 b is suppressed. Accordingly, the vibration can be confined inthe quartz crystal blank 110.

The inclination angle of the upper surface 116 a at a portion where theupper surface 116 a is connected to a short side of the quartz crystalblank 110 on the positive Z′-axis side (i.e., one side in the firstdirection), that is, at a portion near the boundary between the mainsurface 112 of the quartz crystal blank 110 and the upper surface 116 aof the coupling member 111 a is smaller than the inclination angle ofthe lower surface 118 a at a portion where the lower surface 118 a isconnected to a short side of the quartz crystal blank 110 on thepositive Z′-axis side (i.e., one side in the first direction), that is,at a portion near the boundary between the main surface 114 of thequartz crystal blank 110 and the lower surface 118 a of the couplingmember 111 a. In other words, the upper surface 116 a is gently inclinedin the upward direction toward the frame body 120 and is continuouslyconnected to the upper surface 122 of the frame body 120. The lowersurface 118 a is curved in the upward direction from the boundary thatextends in the X-axis direction toward the frame body 120 and isperpendicularly connected to the inner side surface of the frame body120. Thus, change in angle from the main surface 112 of the quartzcrystal blank 110 via the upper surface 116 a of the coupling member 111a to the upper surface 122 of the frame body 120 is smaller than changein angle from the main surface 114 of the quartz crystal blank 110 viathe lower surface 118 a of the coupling member 111 a and the inner sidesurface of the frame body 120 to the lower surface 124 of the frame body120.

Likewise, the inclination angle of the lower surface 118 b at a portionwhere the lower surface 118 b is connected to a short side of the quartzcrystal blank 110 on the negative Z′-axis side (i.e., the other side inthe first direction), that is, a portion near the boundary between themain surface 114 of the quartz crystal blank 110 and the lower surface118 b of the coupling member 111 b is smaller than the inclination angleof the upper surface 116 b at a portion where the upper surface 116 b isconnected to a short side of the quartz crystal blank 110 on thenegative Z′-axis direction (i.e., the other side in the firstdirection), that is, at a portion near the boundary between the mainsurface 112 of the quartz crystal blank 110 and the upper surface 116 bof the coupling member 111 b. In other words, the lower surface 118 b isgently inclined in the downward direction toward the frame body 120 andis continuously connected to the lower surface 124 of the frame body120. The upper surface 116 b is curved in the downward direction fromthe boundary that extends in the X-axis direction toward the frame body120 and is perpendicularly connected to the inner side surface of theframe body 120. Thus, change in angle from the main surface 114 of thequartz crystal blank 110 via the lower surface 118 b of the couplingmember 111 b to the lower surface 124 of the frame body 120 is smallerthan change in angle from the main surface 112 of the quartz crystalblank 110 via the upper surface 116 b of the coupling member 111 b andthe inner side surface of the frame body 120 to the upper surface 122 ofthe frame body 120.

In such shapes of the coupling members 111 a and 111 b, the extensionelectrodes 132 and 142 described above respectively extend to outer sidesurfaces of the frame body 120 via surfaces (e.g., the upper surface 116a and the lower surface 118 b) whose inclination angles with respect tothe main surfaces 112 and 114 of the quartz crystal blank 110 aresmaller. Thus, in contrast to a structure in which the extensionelectrodes extend via the lower surface 118 a and the upper surface 116b, the extension electrodes are prevented from extending at right anglesat the boundary between the coupling member and the frame body and atthe boundary between the inner side surface of the frame body and theupper surface or the lower surface of the frame body. Accordingly, theprobability of breakage of the extension electrode, which may occur dueto thermal contraction or stress concentration of the extensionelectrode, can be reduced due to this configuration.

Next, referring back to FIG. 1, the lid member 200 and the base member300 will be described. The lid member 200 and the base member 300 areeach an example of a package member and are joined to the quartz crystalresonator 100 so as to contain a part of the quartz crystal resonator100 (at least including the quartz crystal blank 110). The quartzcrystal resonator 100, the lid member 200, and the base member 300 eachhave the substantially the same planar shape, such as a rectangularshape, in plan view as seen in the thickness direction of each member.

The lid member 200 is disposed on the main surface 112 side of thequartz crystal blank 110, and the base member 300 is disposed on themain surface 114 side of the quartz crystal blank 110. The lid member200, the quartz crystal resonator 100, and the base member 300 arestacked in this order to form a three-layer structure.

As illustrated in FIG. 1, the lid member 200 and the base member 300each have a flat plate-like shape. The lid member 200 is joined to theentire periphery of the upper surface 122 of the frame body 120 of thequartz crystal resonator 100, and the base member 300 is joined to theentire periphery of the lower surface 124 of the frame body 120 of thequartz crystal resonator 100. Thus, the quartz crystal blank 110 and thecoupling members 111 a and 111 b are sealed in a cavity, which is ahermetically sealed inner space defined between the lid member 200 andthe base member 300.

It is noted that the material of each of the lid member 200 and the basemember 300 is not particularly limited. However, in the presentembodiment, the material is an AT-cut synthetic quartz crystal that isthe same material as the quartz crystal resonator 100 and that is cut inthe same way as the material of the quartz crystal resonator 100. Thus,because members that are to be joined are made of the same material, itis possible to directly join the lid member 200 to the upper surface 122of the frame body 120 and to directly join the base member 300 to thelower surface 124 of the frame body 120 without using a joining member,such as an adhesive, a brazing alloy, or a glass joining material. It isnot intended that use of a joining member is excluded, and the lidmember 200, the frame body 120, and the base member 300 may be joinedvia a joining member. As the material of each of the lid member 200 andthe base member 300, a material other than a quartz crystal may be used.For example, a glass material or a glass epoxy resin, in which glassfibers are impregnated with an epoxy resin, may be used in alternativeaspects. Moreover, it is noted that the shape of each of the lid member200 and the base member 300 is not limited to a flat plate-like shape.

Next, referring to FIG. 5, outer electrodes will be described. Asillustrated in FIG. 5, in the quartz crystal resonator unit 1 accordingto the present embodiment, outer electrodes 410, 420, 430, and 440 areformed on end surfaces (i.e., end surfaces of the quartz crystalresonator 100, the lid member 200, and the base member 300) and a bottomsurface (i.e., a surface of the base member 300 on a side opposite tothe quartz crystal resonator 100).

The outer electrodes 410, 420, 430, and 440 are each electricallyconnected a corresponding one of the excitation electrode 130 and theexcitation electrode 140 to provide the quartz crystal resonator unit 1with electrical connection to the outside and mountability. As shown,the outer electrode 410 is formed on a surface F1, which is an endsurface of the quartz crystal resonator unit 1 to which the extensionelectrode 132 extends. The outer electrode 420 is formed on a surfaceF2, which is an end surface of the quartz crystal resonator unit 1 towhich the extension electrode 142 extends. The outer electrode 430 iselectrically connected to the outer electrode 410 and is formed on abottom surface F3 of the quartz crystal resonator unit 1 (i.e., asurface on the negative Y′-axis side). The outer electrode 440 iselectrically connected to the outer electrode 420 and is formed on thebottom surface F3 of the quartz crystal resonator unit 1. Thus, thequartz crystal resonator unit 1 has the outer electrodes 410 and 430,which are electrically connected to the excitation electrode 130, andouter electrodes 420 and 440, which are electrically connected to theexcitation electrode 140. With this structure, by applying analternating-current voltage between the excitation electrode 130 and theexcitation electrode 140 of the quartz crystal resonator 100 via theouter electrodes 410 and 430 and the outer electrodes 420 and 440, thequartz crystal blank 110 can be configured to vibrate in a predeterminedvibration mode, such as thickness shear vibration mode, therebyobtaining resonance characteristics due to the vibration.

With the structure described above, the quartz crystal resonator unit 1need not have through portions at both end portions of the quartzcrystal blank 110 in the Z′-axis direction in contrast to, for example,a structure described in Patent Document 1 (hereinafter, referred to asthe “conventional structure”). Therefore, it is possible to provide anappropriate area to the quartz crystal blank 110. The through portions113 a and 113 b are formed at both end portions of the quartz crystalblank 110 in the X-axis direction, and the coupling members 111 a and111 b each have a portion whose thickness is smaller than the thicknessof the quartz crystal blank 110. Thus, leakage of vibration issuppressed, and the vibration can be confined in the quartz crystalblank 110. Accordingly, the size of the quartz crystal resonator unit 1can also be reduced while suppressing deterioration of vibrationcharacteristics.

As further shown, the coupling members 111 a and 111 b are joined fromthe quartz crystal blank 110 to the frame body 120 with widths that aresubstantially the same as those of the short sides of the quartz crystalblank 110, and therefore the strengths of the coupling members againstimpact from the outside can be improved, compared with the conventionalstructure.

With the quartz crystal resonator unit 1, without forming viaelectrodes, the excitation electrode 130 and the excitation electrode140 can be electrically connected to outer electrodes by using theextension electrodes 132 and 142. Accordingly, the connectionreliability of a product is improved, compared with a structureincluding via electrodes.

Moreover, with the quartz crystal resonator unit 1, the extensionelectrodes 132 and 142 extend to outer side surfaces of the frame body120 via surfaces that are gently inclined and that are connected to theframe body 120. Accordingly, the probability of breakage of theextension electrodes is reduced, compared with a structure in which theextension electrodes extend at right angles.

In the present embodiment, the extension electrodes 132 and 142 arerespectively formed so as to surround the entire peripheries of theupper surface 122 and the lower surface 124 of the frame body 120.However, arrangement of the extension electrodes is not particularlylimited. That is, as long as the extension electrodes 132 and 142 extendto one of the outer side surfaces of the frame body 120, the extensionelectrodes 132 and 142 need not surround the entire peripheries of theupper surface 122 or the lower surface 124 of the frame body 120.

The thickness of the frame body 120 need not be larger than thethickness of the quartz crystal blank 110 and may be, for example, thesame as the thickness of the quartz crystal blank. In this case, a spacein which the quartz crystal blank can vibrate may be formed by formingrecesses that are recessed in the Y′-axis direction in surfaces of thelid member and the base member that are joined to the quartz crystalresonator.

In the present embodiment, both of the coupling members 111 a and 111 bhave portions whose thicknesses are smaller than the thickness of thequartz crystal blank 110 as described above. However, at least one ofthe two coupling members may have a portion whose thickness is smallerthan the thickness of the quartz crystal blank 110. The boundary betweenthe quartz crystal blank 110 and the coupling members 111 a and 111 band the boundary between the coupling members 111 a and 111 b and theframe body 120 may be continuously formed, or a step may be formed inthe Y′-axis direction.

Next, referring to the flowchart in FIG. 6 and referring to FIG. 7, amethod of manufacturing the quartz crystal resonator unit 1 according tothe first embodiment will be described. FIG. 6 is a flowchartillustrating the method of manufacturing the quartz crystal resonatorunit 1 according to the first exemplary embodiment of the presentinvention. FIG. 7 is a sectional view illustrating how dissolutionoccurs when a portion between a quartz crystal blank and a frame body isetched. In the present description, a method of manufacturing a quartzcrystal resonator unit by using a wafer-level packaging technology,which performs packaging in a wafer state, will be described as anexample. Hereinafter, for convenience of description, elements that donot change before and after a wafer is divided into individual pieces ofthe quartz crystal resonator units 1 will be denoted by the same termsand numerals.

First, a first substrate is prepared (S10). The first substrate is asubstrate for forming a plurality of quartz crystal resonators 100. Inthe present embodiment, the first substrate is, for example, a quartzcrystal substrate made of an AT-cut synthetic quartz crystal.

Next, the quartz crystal blanks 110, the frame bodies 120, the couplingmembers 111 a and 111 b, and the through portions 113 a and 113 b areformed in the first substrate by photolithography and wet etching (S20).In the present embodiment, a plurality of quartz crystal resonators 100are arranged in such a way that the long sides of the main surfaces 112and 114 of the quartz crystal blanks 110 are parallel to the Z′-axis,the short sides are parallel to the X-axis, and the thicknesses of thequartz crystal blanks 110 are parallel to the Y′-axis. To be specific,by forming a mask on the first substrate and by dissolving the firstsubstrate by wet etching, the quartz crystal blanks 110, the framebodies 120, the coupling members 111 a and 111 b, and the throughportions 113 a and 113 b are formed.

Because a quartz crystal substrate has crystal anisotropy, thedissolution rate differs in accordance with crystal orientation. To bespecific, when a quartz crystal substrate is to be processed in thenormal line direction of a main surface of the quartz crystal substrate(that is, the thickness direction of the quartz crystal substrate), in across section parallel to the Y′X-plane, dissolution easily proceeds inthe normal line direction; but, in a cross section parallel to theY′Z′-plane, dissolution does not proceed in the normal line directionbut proceeds with an inclination toward the Z′-axis direction. Forexample, as illustrated in FIG. 7, when a through portion is to beformed between a quartz crystal blank 10 and a frame body 20, if etchingis started from both main surfaces in the Y′-axis direction, etchingproceeds so as to form inclined surfaces 30 a and 30 b that have anangle θ with respect to the main surfaces of the quartz crystalsubstrate. For example, if the cut angle of AT cut is 35 degrees, theangle θ is about 35 degrees. The etching rate of the inclined surfaces30 a and 30 b, which have the Y-axis of quartz crystal as a normal line,is low, compared with surfaces that have the Z′-axis and the X-axis asnormal lines. Therefore, dissolution of the inclined surfaces 30 a and30 b proceeds slowly in the Z′-axis direction.

That is, as illustrated in FIG. 7, the distance L between the quartzcrystal blank 10 and the frame body 20 immediately before a throughportion is formed between the quartz crystal blank 10 and the frame body20 is represented as L=H/tan θ, where H is the thickness of the quartzcrystal substrate when it is assumed that the thicknesses of the quartzcrystal blank 10 and the frame body 20 are the same. In other words, athrough portion is not formed unless the distance L between the quartzcrystal blank 10 and the frame body 20 satisfies L>H/tan θ. Accordingly,in order to form a through portion along substantially the entireperiphery of a portion between the quartz crystal blank and the framebody, the distance L between the quartz crystal blank and the frame bodyat both end portions of the quartz crystal blank in the Z′-axisdirection satisfies L>H/tan θ. In this case, the distance between thequartz crystal blank and the frame body is large, compared with astructure in which the through portion is not formed. That is, there isa problem in that, if reduction in size of the quartz crystal resonatoris prioritized, the area of the quartz crystal blank decreases; and, ifproviding an appropriate area to the quartz crystal blank isprioritized, the outer shape of the quartz crystal resonator becomeslarge.

In contrast, in the present embodiment, the through portions 113 a and113 b are formed in a direction in which wet etching easily proceeds inthe normal line direction; and, in the direction in which dissolutionbecomes inclined, only the thicknesses of the quartz crystal substrateare reduced without forming a through portion so that the couplingmembers 111 a and 111 b remain between the quartz crystal blank 110 andthe frame body 120. That is, in the present embodiment, L1<Hc/tan θ andL2<Hc/tan θ are satisfied, where L1 and L2 are respectively the lengthsof the coupling members 111 a and 111 b in the Z′-axis direction (seeFIG. 4), and Hc is the thickness of the quartz crystal blank 110. Thus,the size of the quartz crystal resonator 100 can be reduced whileproviding an appropriate area to the quartz crystal blank.

Referring back to FIG. 6, the excitation electrodes 130 and 140 and theextension electrodes 132 and 142 are formed by depositing films of anelectroconductive material by sputtering (S30). Positions where theextension electrodes 132 and 142 are to be formed will not be describedhere, because the positions are the same as those of the quartz crystalresonator 100 described above.

Next, a second substrate and a third substrate are prepared (S40). Thesecond substrate is a substrate for forming a plurality of lid members200, and a third substrate is a substrate for forming a plurality ofbase members 300. The second substrate and the third substrate are each,for example, a quartz crystal substrate made of an AT-cut syntheticquartz crystal.

Next, a stacked member is obtained by joining the second substrate to anupper surface of the first substrate (i.e., a side on which theexcitation electrodes 130 are formed on the quartz crystal blanks 110)and joining a third substrate to a lower surface of the first substrate(i.e., a side on which the excitation electrodes 140 are formed on thequartz crystal blanks 110) (S50). That is, the third substrate, thefirst substrate, and the second substrate are stacked in order in theY′-axis direction and are joined to each other. At this time, the secondsubstrate and the third substrate are joined to the entire peripheriesof the upper surfaces or the lower surfaces of the frame bodies 120 ofthe first substrate. Thus, the plurality of quartz crystal blanks 110 inthe first substrate are sealed by joining the second substrate and thethird substrate. When all of the first substrate, the second substrate,and the third substrate are quartz crystal substrates, joining force dueto intermolecular force is large, and sealability is improved.

Next, a plurality of individual pieces are obtained by cutting thestacked member (S60). The stacked member is cut in the Y′-axis directioninto individual pieces of quartz crystal resonator units by dicing orwire-cutting.

Subsequently, outer electrodes are formed on each individual piece(S70). The outer electrodes are formed on the end surfaces and thebottom surface of the quartz crystal resonator unit by using, forexample, an appropriate combination of sputtering, vacuum deposition,and plating. By forming the outer electrodes, the quartz crystalresonator unit is provided with mountability.

With this manufacturing method, the quartz crystal resonator unit 1 canbe manufactured with reduced size while suppressing deterioration ofvibration characteristics as described above. By arranging the quartzcrystal resonators 100 in the first substrate in such a way that thelong sides of the main surfaces 112 and 114 of the quartz crystal blanks110 are parallel to the Z′-axis and the short sides are parallel to theX-axis, the through portions 113 a and 113 b and the inclined portionsof the coupling members 111 a and 111 b can be formed by using theanisotropy of etching. Accordingly, with a simple manufacturing process,it is possible to form the quartz crystal resonator 100 that can bereduced in size while confining vibration in the quartz crystal blank110.

By using dry etching instead of wet etching, it is possible to performetching in the normal line direction of the main surface of the quartzcrystal substrate. However, etching rate of dry etching is lower thanthat of wet etching. As such, it is necessary to perform etching byarranging wafers one by one in a plane. That is, by using wet etching,it is possible to process a quartz crystal substrate in a shorter timethan by using dry etching and to achieve high mass-productivity. It isnoted that the exemplary embodiment is not intended to the use of wetetching and that the use of dry etching is not be excluded.

Next, referring to FIG. 8, a quartz crystal resonator according to asecond exemplary embodiment of the present invention will be described.FIG. 8 is a sectional view of a quartz crystal resonator 500 accordingto the second embodiment of the present invention, in which,specifically, an extension electrode is different in a sectional viewsimilar to FIG. 4. In the following description, differences from thefirst embodiment will be described.

As illustrated in FIG. 8, the quartz crystal resonator 500 according tothe present embodiment differs from the quartz crystal resonator 100shown in FIG. 4 in the directions in which extension electrodes extend.To be specific, an extension electrode 532, which is electricallyconnected to the excitation electrode 130, extends via the upper surface116 b of the coupling member 111 b to reach an outer side surface of theframe body 120 on the negative Z′-axis side. An extension electrode 542,which is electrically connected to the excitation electrode 140, extendsvia the lower surface 118 a of the coupling member 111 a to reach anouter side surface of the frame body 120 on the positive Z′-axis side.As described above, the directions in which extension electrodes extendare not limited to the directions in which the extension electrodes 132and 142 shown in FIG. 4 extend.

Also with this structure, the quartz crystal resonator 500 can obtainthe same advantages as the quartz crystal resonator 100 as describedabove.

Next, referring to FIG. 9, a quartz crystal resonator according to athird exemplary embodiment of the present invention will be described.FIG. 9 is a sectional view of a quartz crystal resonator 600 accordingto the third embodiment of the present invention, in which,specifically, a quartz crystal blank is different in a sectional viewsimilar to FIG. 4.

In the quartz crystal resonator 100 shown in FIG. 4, the quartz crystalblank 110 has a flat plate-like shape. In the quartz crystal resonator600 shown in FIG. 9, a quartz crystal blank 610 has a mesa shape. To bespecific, the quartz crystal blank 610 includes a middle portion 615including the center in the X-axis direction and the Z′-axis direction,and a peripheral portion 617 that is located around the middle portion615 in plan view of the XZ′-plane and that has a thickness smaller thanthat of the middle portion 615. The middle portion 615 of the quartzcrystal blank 610 has a main surface 612 (first main surface) on thepositive Y′-axis side and a main surface 614 (second main surface) onthe negative Y′-axis side. The entirety of the quartz crystal blank 610has a pair of long sides parallel to the Z′-axis and a pair of shortsides parallel to the X-axis in plan view as seen from the main surface612 side or the main surface 614 side.

As with the coupling members 111 a and 111 b shown in FIG. 4, thecoupling members 611 a and 611 b extend in the Z′-axis direction fromthe pair of short sides at both end portions of the quartz crystal blank610 in the Z′-axis direction, that is, from the boundaries between theperipheral portion 617 of the quartz crystal blank 610 and the couplingmembers 611 a and 611 b while keeping the widths of the short sides, andcouple the quartz crystal blank 610 and the frame body 120 to eachother. An excitation electrode 630 is formed on the main surface 612 ofthe middle portion 615, and an excitation electrode 640 is formed on themain surface 614 of the middle portion 615. Moreover, an extensionelectrode 632, which is electrically connected to the excitationelectrode 630, and an extension electrode 642, which is electricallyconnected to the excitation electrode 640, are formed. The structures ofan upper surface 616 a and a lower surface 618 a of the coupling member611 a, an upper surface 616 b and a lower surface 618 b of the couplingmember 611 b, the excitation electrodes 630 and 640, and the extensionelectrodes 632 and 642 are respectively the same as those of the uppersurface 116 a and the lower surface 118 a of the coupling member 111 ashown in FIG. 4, the upper surface 116 b and the lower surface 118 b ofthe coupling member 111 b, the excitation electrodes 130 and 140, andthe extension electrodes 132 and 142. Therefore, detailed description ofthese elements will be omitted. Moreover, as described above, the shapeof the quartz crystal blank is not limited to a flat plate-like shapehaving a uniform thickness and may have a region having a differentthickness.

With the structure described above, in the quartz crystal resonator 600,the coupling members 611 a and 611 b have portions whose thicknesses aresmaller than the thickness of the peripheral portion 617 of the quartzcrystal blank 610, and advantages the same as those of the quartzcrystal resonator 100 can be obtained as described above. In the quartzcrystal resonator 600, because the quartz crystal blank 610 has a mesashape, the strength of confinement of vibration is increased comparedwith the quartz crystal resonator 100, and vibration characteristics areimproved.

The peripheral portion 617 may be located around the entire periphery soas to surround the four sides of the middle portion 615 in plan view ofthe main surface 612. Alternatively, the peripheral portion 617 may belocated at both end portions of the quartz crystal blank 610 in theZ′-axis direction, and, at both end portions of the quartz crystal blank610 in the X-axis direction, the middle portion 615 may extend to reachthe both ends.

In general, the exemplary quartz crystal resonator units described abovemay be used, for example, as a timing device or a load sensor. When thequartz crystal resonator unit is used as a load sensor for measuring aload in the long-side direction (i.e., the Z′-axis direction), in thelong-side direction related to measurement, the quartz crystal blank iscoupled to the frame body 120 via the coupling members; and, in theshort-side direction (i.e., the X-axis direction) that is not related tomeasurement, the through portions are formed between the quartz crystalblank and the frame body. Accordingly, while maintaining sensitivity inload measurement, the effects due to external factors can be reduced,such as a stress in the short-side direction transmitted to the quartzcrystal blank.

Heretofore, exemplary embodiments of the present invention have beendescribed. The quartz crystal resonator 100 (500, 600) includes thequartz crystal blank 110, the excitation electrodes 130 and 140, theframe body 120 that surrounds the quartz crystal blank 110, and thecoupling members 111 a and 111 b that couple the quartz crystal blank110 and the frame body 120 to each other. The coupling members 111 a and111 b extend from the quartz crystal blank 110 to the frame body 120with the widths of the short sides of the quartz crystal blank 110. Atleast one of the coupling members 111 a and 111 b has a portion whosethickness is smaller than a region of the quartz crystal blank 110 wherethe excitation electrode 130 and the excitation electrode 140 face eachother. Thus, the quartz crystal resonator 100 (500, 600) need not havethrough portions at both end portions of the quartz crystal blank 110 inthe Z′-axis direction. Therefore, for example, it is possible to providean appropriate area to the quartz crystal blank 110, compared with theconventional structure. Moreover, because the coupling members 111 a and111 b have portions whose thicknesses are smaller than the thickness ofthe quartz crystal blank 110, vibration can be confined in the quartzcrystal blank 110. Accordingly, the size of the quartz crystal resonatorcan be reduced while suppressing deterioration of vibrationcharacteristics. Furthermore, because the coupling members 111 a and 111b are coupled to the frame body 120 with the widths of the short sidesof the quartz crystal blank 110, strength against impact from theoutside is improved, compared with the conventional structure.

In the quartz crystal resonator 600, the quartz crystal blank 610includes the middle portion 615 and the peripheral portion 617 that islocated around the middle portion 615. As shown, the thickness of themiddle portion 615 is larger than the thickness of the peripheralportion 617, and at least one of the coupling members 611 a and 611 bhas a portion whose thickness is smaller than the thickness of theperipheral portion 617 of the quartz crystal blank 610. Because thequartz crystal blank 610 has a mesa shape as described above, thestrength of confinement of vibration is increased compared with thequartz crystal resonator 100, and vibration characteristics areimproved.

The quartz crystal resonator 100 (500, 600) includes the extensionelectrodes 132 and 142 that are respectively electrically connected tothe excitation electrodes 130 and 140 and that extend to reach outerside surfaces of the frame body 120 via the coupling members 111 a and111 b. Thus, without forming via electrodes, the excitation electrodes130 and 140 can be electrically connected to outer electrodes.Accordingly, the connection reliability of a product is improved,compared with a structure having via electrodes.

In the quartz crystal resonator 100 (500, 600), the lower surface 118 aof the coupling member 111 a has an inclined portion that is inclined inthe upward direction with respect to the main surface 114 from thequartz crystal blank 110 toward the frame body 120, and the uppersurface 116 b of the coupling member 111 b has an inclined portion thatis inclined in the downward direction with respect to the main surface112 from the quartz crystal blank 110 toward the frame body 120. Thus,the thicknesses of the quartz crystal blank 110 and the coupling members111 a and 111 b and the thicknesses of the coupling members 111 a and111 b and the frame body 120 differ from each other at the boundariestherebetween. Accordingly, leakage of vibration of the quartz crystalblank 110 to the frame body 120 via the coupling members 111 a and 111 bis suppressed.

It is noted that the shapes of the upper surface 116 a of the couplingmember 111 a and the lower surface 118 b of the coupling member 111 bare not particularly limited. For example, the upper surface 116 a ofthe coupling member 111 a may have an inclined portion that is inclinedin the upward direction with respect to the main surface 112 from thequartz crystal blank 110 toward the frame body 120 and that extends toreach the upper surface 122 of the frame body 120, and the lower surface118 b of the coupling member 111 b may have an inclined portion that isinclined in the downward direction with respect to the main surface 114from the quartz crystal blank 110 toward the frame body 120 and thatextends to reach the lower surface 124 of the frame body 120.

In the quartz crystal resonator 100 (600), the inclination angle of aportion of the upper surface 116 a of the coupling member 111 a near theboundary with the quartz crystal blank 110 is smaller than theinclination angle of a portion of the lower surface 118 a of thecoupling member 111 a near the boundary with the quartz crystal blank110; the inclination angle of a portion of the lower surface 118 b ofthe coupling member 111 b near the boundary with the quartz crystalblank 110 is smaller than the inclination angle of a portion of theupper surface 116 b of the coupling member 111 b near the boundary withthe quartz crystal blank 110; the extension electrode 132 extends viathe upper surface 116 a of the coupling member 111 a to reach an outerside surface of the frame body 120 in the Z′-axis direction on the uppersurface side; and the extension electrode 142 extends via the lowersurface 118 b of the coupling member 111 b to reach an outer sidesurface of the frame body 120 in the Z′-axis direction on the lowersurface side. Thus, the extension electrodes 132 and 142 are preventedfrom extending at right angles. Accordingly, it is possible to reducethe probability of breakage of the extension electrodes due to thermalcontraction or stress concentration.

Moreover, the thickness of the frame body is not particularly limited.For example, the thickness of the frame body 120 may be equal to orlarger than the thickness of the region of the quartz crystal blank 110where the excitation electrode 130 and the excitation electrode 140 faceeach other. The lower surface 118 a of the coupling member 111 a and theupper surface 116 b of the coupling member 111 b may be, for example,perpendicularly connected to the inner side surface of the frame body120.

As described herein, the quartz crystal resonator 100 (500, 600)includes the quartz crystal blank 110, the excitation electrodes 130 and140, the frame body 120 that surrounds the quartz crystal blank 110, andthe coupling members 111 a and 111 b that couple the quartz crystalblank 110 and the frame body 120 to each other. The coupling members 111a and 111 b extend from the quartz crystal blank 110 to the frame body120 with the widths of the short sides of the quartz crystal blank 110.Between both end portions of the quartz crystal blank 110 in the X-axisdirection and the frame body 120, the through portions 113 a and 113 bare formed so as to each extend over the length of the quartz crystalblank 110 and the coupling members 111 a and 111 b in the Z′-axisdirection. The upper surface and the lower surface of the couplingmember 111 a have inclined surfaces that are inclined upward from thequartz crystal blank 110 toward the frame body 120. The upper surfaceand the lower surface of the coupling member 111 b have inclinedsurfaces that are inclined downward from the quartz crystal blank 110toward the frame body 120. Thus, because the quartz crystal resonator100 (500, 600) need not have through portions at both end portions ofthe quartz crystal blank 110 in the Z′-axis direction, for example, itis possible to provide an appropriate area to the quartz crystal blank110, compared with the conventional structure. Moreover, because theupper surface and the lower surface of the coupling members 111 a and111 b have the inclined portions, the coupling members 111 a and 111 bhave portions whose thicknesses are smaller than the thickness of thequartz crystal blank 110, and therefore vibration can be confined in thequartz crystal blank 110. Accordingly, the size of the quartz crystalresonator unit can be reduced while suppressing deterioration ofvibration characteristics. Furthermore, because the coupling members 111a and 111 b are connected to the frame body 120 with the widths of theshort sides of the quartz crystal blank 110, strength against impactfrom the outside is improved, compared with the conventional structure.

It is also noted that the shapes of the coupling members are notparticularly limited. For example, the upper surface and the lowersurface of each of the coupling members 111 a and 111 b may each have acurved shape. To be specific, for example, the inclined portion of theupper surface 116 a of the coupling member 111 a may have a curved shapethat is recessed downward, the inclined portion of the lower surface 118a of the coupling member 111 a may have a curved shape that is recessedupward, the inclined portion of the upper surface 116 b of the couplingmember 111 b may have a curved shape that is recessed downward, and theinclined portion of the lower surface 118 b of the coupling member 111 bmay have a curved shape that is recessed upward.

The quartz crystal resonator 100 (500, 600) is made of an AT-cut quartzcrystal, the long sides of the quartz crystal blank 110 are parallel tothe Z′-axis, the short sides are parallel to the X-axis, and thethickness is parallel to the Y′-axis. Thus, by forming the quartzcrystal resonator 100 (500, 600) by wet etching, the through portions113 a and 113 b and the coupling members 111 a and 111 b can be formedby using the anisotropy of etching. Accordingly, the quartz crystalresonator 100 (500, 600) can be formed by a simple manufacturing processas described herein.

In the quartz crystal resonator 100 (500, 600), L1<Hc/tan θ andL2<Hc/tan θ are satisfied, where L1 is the length of the coupling member111 a in the Z′-axis direction, L2 is the length of the coupling member111 b in the Z′-axis direction, Hc is the thickness of a region of thequartz crystal blank 110 where the excitation electrode 130 and theexcitation electrode 140 face each other, and θ is the cut angle of thequartz crystal resonator. Thus, the size of the quartz crystal resonatorcan be reduced while providing an appropriate area to the quartz crystalblank 110.

The quartz crystal resonator unit 1 includes, for example, the quartzcrystal resonator 100 (500, 600), and the lid member 200 and the basemember 300 that are joined to the frame body 120. Thus, the quartzcrystal blank 110 and the coupling members 111 a and 111 b are sealed ina space.

The quartz crystal resonator unit 1 further includes the outerelectrodes 410, 420, 430, and 440 that are formed on end surfaces of thequartz crystal resonator 100 (500, 600) and the base member 300 and eachof which is electrically connected to a corresponding one of theexcitation electrodes 130 and 140. Thus, the quartz crystal resonatorunit 1 can be electrically connected to the outside and can havemountability.

In the quartz crystal resonator unit 1, the lid member 200 and the basemember 300 are each made of an AT-cut quartz crystal. Thus, it ispossible to directly join the base member 300, the quartz crystalresonator 100 (500, 600), and the lid member 200 to each other withoutusing a joining member, such as an adhesive or a glass joining material.

As described herein a method of manufacturing a quartz crystal resonator100 (500, 600) is provided that includes (a) preparing a first substratemade of an AT-cut quartz crystal; (b) forming, by wet etching the firstsubstrate, the quartz crystal blank 110 that has the main surfaces 112and 114 facing each other, the frame body 120 that surrounds the quartzcrystal blank 110, and the coupling members 111 a and 111 b that couplethe quartz crystal blank 110 and the frame body 120 to each other atboth end portions of the quartz crystal blank 110 in the Z′-axisdirection; and (c) forming the excitation electrode 130 on the mainsurface 112 and forming the excitation electrode 140 on the main surface114. Moreover, step (b) includes separating both end portions of thequartz crystal blank 110 in the X-axis direction from the frame body120, extending the coupling members 111 a and 111 b from a pair of shortsides of the quartz crystal blank 110 with the widths of the short sidesto reach the frame body 120, and making the thickness of at least aportion of at least one of the coupling members 111 a and 111 b smallerthan the thickness of a region of the quartz crystal blank 110 where theexcitation electrode 130 and the excitation electrode 140 face eachother. Thus, it is possible to form the through portions 113 a and 113 band the coupling members 111 a and 111 b by using the anisotropy ofetching. Accordingly, the quartz crystal resonator 100 (500, 600) can beformed with a simple manufacturing process.

In the quartz crystal resonator 100 (500, 600), the coupling members 111a and 111 b each have an upper surface and a lower surface; and in (b),by wet etching the first substrate, an inclined portion is formed in thelower surface 118 a of the coupling member 111 a, the inclined portionbeing inclined in the upward direction with respect to the main surface114 from the quartz crystal blank 110 toward the frame body 120, and aninclined portion is formed in the upper surface 116 b of the couplingmember 111 b, the inclined portion being inclined in the downwarddirection with respect to the main surface 112 from the quartz crystalblank 110 toward the frame body 120. Thus, by using the anisotropy ofetching, it is possible to make the thicknesses of the quartz crystalblank 110 and the coupling members 111 a and 111 b differ from thethicknesses of the coupling members 111 a and 111 b and the frame body120 at the boundaries therebetween. Accordingly, leakage of vibration ofthe quartz crystal blank 110 to the frame body 120 via the couplingmembers 111 a and 111 b is suppressed.

In the quartz crystal resonator 100 (500, 600), the frame body 120 mayhave the upper surface 122 and the lower surface 124; and, for example,in step (b), by wet etching the first substrate, an inclined portion maybe formed in the upper surface 116 a of the coupling member 111 a, theinclined portion being inclined in the upward direction with respect tothe main surface 112 from the quartz crystal blank 110 toward the framebody 120 and extending to reach the upper surface 122 of the frame body120, and an inclined portion may be formed in the lower surface 118 b ofthe coupling member 111 b, the inclined portion being inclined in thedownward direction with respect to the main surface 114 from the quartzcrystal blank 110 toward the frame body 120 and extending to reach thelower surface of the frame body 120.

In step (b), an inclination angle of a portion of the upper surface 116a of the coupling member 111 a near the boundary with the quartz crystalblank 110 is made smaller than an inclination angle of a portion of thelower surface 118 a of the coupling member 111 a near the boundary withthe quartz crystal blank 110, and an inclination angle of a portion ofthe lower surface 118 b of the coupling member 111 b near the boundarywith the quartz crystal blank 110 is made smaller than an inclinationangle of a portion of the upper surface 116 b of the coupling member 111b near the boundary with the quartz crystal blank 110; and (c) furtherincludes forming the extension electrode 132 that is electricallyconnected to the excitation electrode 130 and that extends via the uppersurface 116 a of the coupling member 111 a to reach an outer sidesurface of the frame body 120 in the Z′-axis direction on the uppersurface side, and forming the extension electrode 142 that iselectrically connected to the excitation electrode 140 and that extendsvia the lower surface 118 b of the coupling member 111 b to reach anouter side surface of the frame body 120 in the Z′-axis direction on thelower surface side. Thus, the extension electrodes 132 and 142 areprevented from extending at right angles. Accordingly, the probabilityof breakage of the extension electrode due to thermal contraction andstress concentration can be reduced.

As described herein, a method of manufacturing a quartz crystalresonator 100 (500, 600) is provided that includes (a) preparing a firstsubstrate made of an AT-cut quartz crystal; (b) forming, by wet etchingthe first substrate, the quartz crystal blank 110 that has the mainsurfaces 112 and 114 facing each other, the frame body 120 thatsurrounds the quartz crystal blank 110, the coupling members 111 a and111 b that couple the quartz crystal blank 110 and the frame body 120 toeach other at both end portions of the quartz crystal blank 110 in theZ′-axis direction, the through portions 113 a and 113 b that are formedbetween both end portions of the quartz crystal blank 110 in the X-axisdirection and the frame body 120 over a length of the quartz crystalblank 110 and the coupling members 111 a and 111 b in the Z′-axisdirection; and (c) forming the excitation electrode 130 on the mainsurface 112 and forming the excitation electrode 140 on the main surface114. In step (b), the main surfaces 112 and 114 are located between theupper surface 122 and the lower surface 124 of the frame body 120 in theY′-axis direction, inclined surfaces are formed on the upper surface 116a and the lower surface 118 a of the coupling member 111 a, the inclinedsurfaces extending from the quartz crystal blank 110 toward the framebody 120 upward in the Y′-axis direction, and inclined surfaces areformed on the upper surface 116 b and the lower surface 118 b of thecoupling member 111 b, the inclined surfaces extending from the quartzcrystal blank 110 toward the frame body 120 downward in the Y′-axisdirection. Thus, it is possible to form the through portions 113 a and113 b and the coupling members 111 a and 111 b by using the anisotropyof etching. Accordingly, the quartz crystal resonator 100 (500, 600) canbe formed with a simple manufacturing process.

Moreover, a method of manufacturing the quartz crystal resonator unit 1is provided that includes, for example, the method of manufacturing thequartz crystal resonator 100 (500, 600), (d) preparing a secondsubstrate for forming the lid member 200, (e) preparing a thirdsubstrate for forming the base member 300, (f) joining the firstsubstrate and the second substrate to each other in such a way that thelid member 200 is joined to the frame body 120 on the excitationelectrode 130 side, and (g) joining the first substrate and the thirdsubstrate to each other in such a way that the base member 300 is joinedto the frame body 120 on the excitation electrode 140 side.

In each of the embodiments described above, as an example of a quartzcrystal resonator that is AT-cut, a quartz crystal resonator in which aquartz crystal blank has long sides that are parallel to the Z′-axis andshort sides that are parallel to the X-axis has been described. However,it is noted that the exemplary embodiments are not limited to this. Forexample, an AT-cut quartz crystal resonator having short sides that areparallel to the Z′-axis and long sides that are parallel to the X-axismay be used. Alternatively, a quartz crystal resonator including aquartz crystal substrate that is not AT-cut but is, for example, BT-cutmay be used.

The exemplary embodiments, which have been described above in order tofacilitate understanding the present invention, do not limit the scopeof the present invention. The present invention may be modified withinthe spirit and scope thereof and includes the equivalents thereof. Thatis, a modification of each of the embodiments that is appropriatelymodified in design by a person having ordinary skill in the art isincluded in the scope of the present invention as long as themodification has the features of the present invention. For example,elements of each of the embodiments; and the arrangement, the materials,the shapes, and the sizes of the elements are not limited to thosedescribed above as examples and may be modified as appropriate. Elementsof the embodiments may be used in a combination as long as thecombination is technologically feasible, and such combination is alsoincluded in the scope of the present invention as long as thecombination has the features of the present invention.

REFERENCE SIGNS LIST

-   -   1 quartz crystal resonator unit    -   100, 500, 600 quartz crystal resonator    -   110, 610 quartz crystal blank    -   111 a, 111 b, 611 a, 611 b coupling member    -   113 a, 113 b through portion    -   120 frame body    -   130, 140, 630, 640 excitation electrode    -   132, 142, 532, 542, 632, 642 extension electrode    -   200 lid member    -   300 base member    -   410, 420, 430, 440 outer electrode

The invention claimed is:
 1. A method of manufacturing a quartz crystalresonator, comprising: preparing a first substrate from a quartz crystalthat is AT-cut, such that, when an X-axis, a Y-axis, and a Z-axis arecrystal axes of the quartz crystal and a Y′-axis and a Z′-axis arerespectively axes by rotating the Y-axis and the Z-axis around theX-axis by a predetermined angle in a direction from the Y-axis towardthe Z-axis, surfaces of the quartz crystal that are defined by theX-axis and the Z′-axis are main surfaces; forming, by wet etching thefirst substrate: a body having first and second main surfaces that faceeach other and that include, in a plan view of the first or second mainsurfaces, a pair of long sides that extend in the Z′-axis direction anda pair of short sides that extend in the X-axis direction, a frame thatsurrounds the body, and first and second coupling portions that couplethe body to the frame at respective ends of the body in the Z′-axisdirection; and forming a first excitation electrode on the first mainsurface and a second excitation electrode on the second main surfacethat faces the first excitation electrode, wherein the wet etching ofthe first substrate includes: separating both ends of the body in theX-axis direction from the frame, extending the first coupling portion inthe Z′-axis direction from one of the pair of short sides of the bodywith a width of the short side to reach the frame, extending the secondcoupling portion in the Z′-axis direction from the other of the pair ofshort sides of the body with a width of the short side to reach theframe, and making a thickness in the Y′-axis direction of at least aportion of at least one of the first and second coupling portionssmaller than a thickness in the Y′-axis direction of a region of thebody where the first and second excitation electrodes face each other.2. The method of manufacturing a quartz crystal resonator according toclaim 1, wherein the first and second coupling portions each have anupper surface on a side of the first main surface and a lower surface ona side of the second main surface, and wherein the wet etching of thefirst substrate comprises: forming an inclined portion in the lowersurface of the first coupling portion that is inclined in an upwarddirection with respect to the second main surface from the body towardsthe frame, and forming an inclined portion in the upper surface of thesecond coupling portion that is inclined in a downward direction withrespect to the first main surface from the body towards the frame. 3.The method of manufacturing a quartz crystal resonator according toclaim 2, wherein the frame has an upper surface on the side of the firstmain surface of the body and a lower surface on the side of the secondmain surface of the body, and wherein the wet etching of the firstsubstrate further comprises: forming an inclined portion in the uppersurface of the first coupling portion that is inclined in the upwarddirection with respect to the first main surface from the body towardsthe frame and that extends to the upper surface of the frame, andforming an inclined portion in the lower surface of the second couplingportion that is inclined in the downward direction with respect to thesecond main surface from the body towards the frame and that extends tothe lower surface of the frame.
 4. The method of manufacturing a quartzcrystal resonator according to claim 3, wherein, the wet etching of thefirst substrate further comprises: forming an inclination angle of aportion of the upper surface of the first coupling portion that isconnected to a first short side of the body smaller than an inclinationangle of a portion of the lower surface of the first coupling portionthat is connected to the first short side of the body; and forming aninclination angle of a portion of the lower surface of the secondcoupling portion that is connected to a second short side of the bodysmaller than an inclination angle of a portion of the upper surface ofthe second coupling portion that is connected to the second short sideof the body.
 5. The method of manufacturing a quartz crystal resonatoraccording to claim 4, wherein the forming of the first and secondexcitation electrodes further comprises: forming a first extensionelectrode that is electrically connected to the first excitationelectrode and that extends via the upper surface of the first couplingportion to a first outer side surface of the frame in the Z′-axisdirection on the upper surface side; and forming a second extensionelectrode that is electrically connected to the second excitationelectrode and that extends via the lower surface of the second couplingportion to a second outer side surface of the frame in the Z′-axisdirection on the lower surface side.
 6. The method of manufacturing aquartz crystal resonator according to claim 1, wherein L1<Hc/tan θ andL2<Hc/tan θ are satisfied, where L1 is a length of the first couplingportion in the Z′-axis direction, L2 is a length of the second couplingportion in the Z′-axis direction, Hc is a length in the Y′-axisdirection of the region of the body where the first excitation electrodefaces the second excitation electrode, and θ is a cut angle of thequartz crystal resonator.
 7. The method of manufacturing a quartzcrystal resonator according to claim 1, wherein the forming of the body,by wet etching the first substrate, comprises forming the body toinclude a middle portion that includes a center in the Z′-axis directionand the X-axis direction and a peripheral portion that is located aroundthe middle portion in the plan view of the first or second mainsurfaces, such that the middle portion has a thickness in the Y′-axisdirection that is larger than a thickness of the peripheral portion inthe Y′-axis direction, and at least a portion of at least one of thefirst and second coupling portions has a thickness smaller than thethickness of the peripheral portion of the body in the Y′-axisdirection.
 8. The method of manufacturing a quartz crystal resonatoraccording to claim 2, wherein the forming of the frame, by wet etchingthe first substrate, comprises forming the frame to have a thickness inthe Y′-axis direction that is equal to or larger than the thickness ofthe region of the body where the first excitation electrode and thesecond excitation electrode face each other, with the upper surface ofthe first coupling portion being perpendicularly connected to an innerside surface of the frame, and the lower surface of the second couplingportion being perpendicularly connected to the inner side surface of theframe.
 9. A method of manufacturing a quartz crystal resonator unit,comprising: manufacturing a quartz crystal resonator according to claim1; preparing a second substrate for forming a lid; preparing a thirdsubstrate for forming a base; joining the first substrate to the secondsubstrate such that the lid is joined to the frame on a side of thefirst excitation electrode; and joining the first substrate to the thirdsubstrate such that the base is joined to the frame on a side of thesecond excitation electrode.
 10. A method of manufacturing a quartzcrystal resonator, comprising: preparing a first substrate from a quartzcrystal that is AT-cut, such that, when an X-axis, a Y-axis, and aZ-axis are crystal axes of the quartz crystal and a Y′-axis and aZ′-axis are respectively axes by rotating the Y-axis and the Z-axisaround the X-axis by a predetermined angle in a direction from theY-axis toward the Z-axis, surfaces of the quartz crystal that aredefined by the X-axis and the Z′-axis are main surfaces; forming, by wetetching the first substrate: a body having first and second mainsurfaces that face each other and that include, in a plan view of thefirst or second main surfaces, a pair of long sides that extend in theZ′-axis direction and a pair of short sides that extend in the X-axisdirection, a frame that has an inner side surface that surrounds thebody and an upper and lower surfaces that are respectively located on anupper side and a lower side in the Y′-axis direction, a first couplingportion that extends in the Z′-axis direction so as to couple one of thepair of short sides of the body to the inner side surface of the frameand that has an upper surface and a lower surface that are respectivelylocated on an upper side and a lower side in the Y′-axis direction, asecond coupling portion that extends in the Z′-axis direction so as tocouple the other of the pair of short sides of the body to the innerside surface of the frame and that has an upper surface and a lowersurface that are respectively located on an upper side and a lower sidein the Y′-axis direction, and a first and second through portionsbetween both ends of the body in the X-axis direction and the frame,with the first and second through portions each extending over a lengthof the body and the first and second coupling portions in the Z′ axisdirection; and forming a first excitation electrode on the first mainsurface and a second excitation electrode on the second main surfacethat faces the first excitation electrode, wherein the first and secondmain surfaces are located between the upper surface and the lowersurface of the frame in the Y′-axis direction, and wherein the wetetching of the first substrate includes: forming an inclined portion ineach of the upper surface and the lower surface of the first couplingportion that is inclined upward in the Y′-axis direction from the bodytowards the frame, and forming an inclined portion in each of the uppersurface and the lower surface of the second coupling portion that isinclined downward in the Y′-axis direction from the body towards theframe.
 11. The method of manufacturing a quartz crystal resonatoraccording to claim 10, wherein the wet etching of the first substratefurther comprises forming the first and second coupling portions to eachcomprise a width extending in the second direction that is substantiallya same width as the respective pair of short sides of the body.
 12. Themethod of manufacturing a quartz crystal resonator according to claim10, wherein the wet etching of the first substrate includes making athickness in the Y′-axis direction of at least a portion of at least oneof the first and second coupling portions smaller than a thickness inthe Y′-axis direction of a region of the body where the first and secondexcitation electrodes face each other.
 13. The method of manufacturing aquartz crystal resonator according to claim 10, wherein the forming ofthe first and second excitation electrodes further comprises: forming afirst extension electrode that is electrically connected to the firstexcitation electrode and that extends via the upper surface of the firstcoupling portion to a first outer side surface of the frame in theZ′-axis direction; and forming a second extension electrode that iselectrically connected to the second excitation electrode and thatextends via the lower surface of the second coupling portion to a secondouter side surface of the frame in the Z′-axis direction.
 14. The methodof manufacturing a quartz crystal resonator according to claim 10,wherein the forming of the body, by wet etching the first substrate,comprises forming the body to include a middle portion that includes acenter in the Z′-axis direction and the X-axis direction and aperipheral portion that is located around the middle portion in the planview of the first or second main surfaces, such that the middle portionhas a thickness in the Y′-axis direction that is larger than a thicknessof the peripheral portion in the Y′-axis direction, and at least aportion of at least one of the first and second coupling portions has athickness smaller than the thickness of the peripheral portion of thebody in the Y′-axis direction.
 15. A method of manufacturing a quartzcrystal resonator unit, comprising: manufacturing a quartz crystalresonator according to claim 10; preparing a second substrate forforming a lid; preparing a third substrate for forming a base; joiningthe first substrate to the second substrate such that the lid is joinedto the frame on a side of the first excitation electrode; and joiningthe first substrate to the third substrate such that the base is joinedto the frame on a side of the second excitation electrode.
 16. A methodof manufacturing a quartz crystal resonator, comprising: wet etching asubstrate to form: a body having first and second main surfaces thatface each other and that includes a pair of long sides that extend in afirst direction and a pair of short sides that extend in a second, aframe that surrounds the body, and first and second coupling portionsthat couple the body to the frame at respective ends of the body in thefirst direction; and forming a first excitation electrode on the firstmain surface and a second excitation electrode on the second mainsurface that faces the first excitation electrode, wherein the wetetching of the first substrate includes: separating both ends of thebody in the second direction from the frame, extending the firstcoupling portion in the first direction from one of the pair of shortsides of the body to reach the frame, with the first coupling portionhaving a same width as the respective short side, extending the secondcoupling portion in the first direction from the other of the pair ofshort sides of the body to reach the frame, with the second couplingportion having a same width as the respective short side, and making athickness in a third direction of at least a portion of at least one ofthe first and second coupling portions smaller than a thickness in thethird direction of a region of the body where the first and secondexcitation electrodes face each other, with the third direction beingorthogonal to the first and second main surfaces of the body.
 17. Themethod of manufacturing a quartz crystal resonator according to claim16, further comprising preparing the substrate from a quartz crystalthat is AT-cut, such that, when an X-axis, a Y-axis, and a Z-axis arecrystal axes of the quartz crystal and a Y′-axis and a Z′-axis arerespectively axes by rotating the Y-axis and the Z-axis around theX-axis by a predetermined angle in a direction from the Y-axis towardthe Z-axis, surfaces of the quartz crystal that are defined by theX-axis and the Z′-axis are the first and second main surfaces.
 18. Themethod of manufacturing a quartz crystal resonator according to claim16, wherein the first and second coupling portions each have an uppersurface on a side of the first main surface and a lower surface on aside of the second main surface, and wherein the wet etching of thesubstrate comprises: forming an inclined portion in the lower surface ofthe first coupling portion that is inclined in an upward direction withrespect to the second main surface from the body towards the frame; andforming an inclined portion in the upper surface of the second couplingportion that is inclined in a downward direction with respect to thefirst main surface from the body towards the frame.
 19. The method ofmanufacturing a quartz crystal resonator according to claim 18, whereinthe frame has an upper surface on the side of the first main surface ofthe body and a lower surface on the side of the second main surface ofthe body, and wherein the wet etching of the substrate furthercomprises: forming an inclined portion in the upper surface of the firstcoupling portion that is inclined in the upward direction with respectto the first main surface from the body towards the frame and thatextends to the upper surface of the frame; and forming an inclinedportion in the lower surface of the second coupling portion that isinclined in the downward direction with respect to the second mainsurface from the body towards the frame and that extends to the lowersurface of the frame.
 20. The method of manufacturing a quartz crystalresonator according to claim 19, wherein the wet etching of thesubstrate further comprises: forming an inclination angle of a portionof the upper surface of the first coupling portion that is connected toa first short side of the body smaller than an inclination angle of aportion of the lower surface of the first coupling portion that isconnected to the first short side of the body, forming an inclinationangle of a portion of the lower surface of the second coupling portionthat is connected to a second short side of the body smaller than aninclination angle of a portion of the upper surface of the secondcoupling portion that is connected to the second short side of the body,and wherein the forming of the first and second excitation electrodesfurther comprises: forming a first extension electrode that iselectrically connected to the first excitation electrode and thatextends via the upper surface of the first coupling portion to a firstouter side surface of the frame in the first direction on the uppersurface side, and forming a second extension electrode that iselectrically connected to the second excitation electrode and thatextends via the lower surface of the second coupling portion to a secondouter side surface of the frame in the first direction on the lowersurface side.